Fermentation stops after 3 days!

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Fermentation stops after 3 days!

Unread postby Crockett49 » Wed Jan 28, 2015 12:52 am

Hi. I have done three brews with my 50L Braumeister. After boil the gravities have been around the 1.050 mark which has been the target. I ferment in a 14.5 US gal Blichmann fermenter with the remainder in a 15L plastic fermenter. Temperatures have been a constant 22 degrees Celsius during the fermenting - bit hard to get it cooler in an Australian summer. The fermenting has been quite active during the first three days then seems to stop. Gravity readings over consecutive 24 hours periods after that shows no movement. Final gravity readings have been in the 1.020s with the last brew (a milk stout) at 1.031. I have tried adding more yeast mid fermentation as well as aerating with a filtered air pump when I pitch the yeast and after two days of fermenting in case it was a lack of oxygen issue.
I am milling my own grain and the first two brews were at 1.2 millimetres and the last I increased to 1.4mm to see if that would help with fermenting - it didn't.
Any ideas as to what I may be doing wrong to cause the fermenting to stop early would be greatly appreciated!
The first two brews tasted fine but were only mid strength at best. The stout is going to be very light...
Happy Brewing!
Craig
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Re: Fermentation stops after 3 days!

Unread postby cpa4ny » Wed Jan 28, 2015 1:24 am

Some usual suspects for fermentation crapping out too early may be:

a.) Yeast - was it fresh and did you have a chance to make a starter? (or rehydrate it if it is dry yeast)

b.) Did you have a chance to oxygenate the wort prior to pitching yeast?

c.) What was the pH like before you pitched the yeast? Dark grains in the stout may have pulled the pH too low. I usually add a couple of grams of baking soda to counteract that.

Hope that helps :beer:
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Re: Fermentation stops after 3 days!

Unread postby DWP » Wed Jan 28, 2015 2:46 am

What have your mash temps been at?
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Re: Fermentation stops after 3 days!

Unread postby Crockett49 » Wed Jan 28, 2015 3:39 am

Thanks for the responses.
First batch just pitched the dry yeast as I used to do with extract brewing (had no troubles with the extract brews just pitching the dry yeast in), when it stopped after a few days I made a starter and pitched that as well as buying an air pump to aerate it.
Second batch pitched in a starter made from the dry yeast as well as aerating the brew when I pitch the yeast for an hour.
Third batch I pitch in a starter made with liquid yeast as well as aerating the brew when I pitched the yeast for an hour then again two days later for a further hour.
1st two batches I used the default Braumeister settings:
mash in at 38C
30 minutes at 63C
30 mins at 73C
15 mins at 78C
Remove grain, add hops and boil for 60 mins

With the 3rd batch I increased time at 63C and 73C to 35 minutes each.

I haven't tested the pH of the wort before it goes into the fermenter. What level should I be aiming for?
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Re: Fermentation stops after 3 days!

Unread postby dinnerstick » Wed Jan 28, 2015 7:11 am

in addition to the others, and assuming the yeast was fresh and alive when you got it
what is the yeast strain?
are there possibly temperature fluctuations? doesn't seem so with a large enough volume..
i am not a big believer in the idea that a bit of tinkering with your mash schedule will have a great effect on your final gravity, certainly not 10 points, when you are dong a standard enough schedule. unless you are just not getting conversion, like if you have REALLY poor circulation through the malt tube and the middle bit never gets to sacc temp.... unlikely but do you ever do an iodine test? is there any sign of poor circulation, or of weird temperatures in the grain bed?
on starters with dry yeast: making a starter with dry yeast is generally frowned upon, unless done to save money, but then dry yeast is so cheap. the yeast companies are really good at building up the reserves of sterols and fatty acids, the kind of stuff that the yeast really need when actively growing, and the sort of compounds they absolutely need oxygen to synthesize. we can't match the yeast labs in stimulating sterol etc. production when making a starter at home, so it's usually best to take advantage of their work and pitch dry yeast straight (after rehydrating of course). But certainly no harm done, as long as you treat them well and they get enough oxygen in the starter and at pitching time.
Wort pH, it should be around mash pH, low to mid 5's, if its dropping into the 4's then maybe a cause for concern. Many yeasts like S05 will happily ferment berlinners that are in the mid 3's, but surely some strains are more sensitive.
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Re: Fermentation stops after 3 days!

Unread postby cpa4ny » Wed Jan 28, 2015 8:00 am

The mash temps look perfectly fine and should be able to produce well fermentable wort.

The ideal pH for a mash is range between 5.2 - 5.6; I personally feel that my beers made a quantum leap once I purchased a pH meter and started to pay more attention to mash pH / water profiles.

Did you mash roast barley / black patent malt with the rest of the malts from the beginning or added them later?

BYO had good article on this: https://byo.com/hops/item/629-fermentab ... ed-brewing

"One final issue is the mash pH. Research has shown that beta-amylase is favored at a somewhat higher pH (~5.5) than alpha-amylase, which has an optimum pH of 5.0. This might suggest increased fermentability with a higher mash pH, but in general, as long as the mash pH is within the recommended range of 5.2–5.6 there are no problems."

My thinking that the high percentage of roasted grains pulled mash pH to ~4.8 - 5.

As we know, alpha-amylase produces dextrinous wort, which cannot be fermented well by brewer's yeast - hence, the issue.

Do you have fermentability issues with your pale ales as well?
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Re: Fermentation stops after 3 days!

Unread postby BrauTim » Wed Jan 28, 2015 1:52 pm

Next time you brew, try the Fast Ferment Test I do this on nearly every brew and especially if changing recipes, yeast, processes etc, that way you will know the limit of attenuation.

Other than that a good stir and raise the temp is all I can suggest, you could try a pitch of Notty as well.
To brew or not to brew, that would be a stupid question !
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Re: Fermentation stops after 3 days!

Unread postby Nesto » Wed Jan 28, 2015 7:46 pm

BrauTim beat me to the Forced Ferment Test! (FYI, Braukaiser wiki is having problems for the last few days - Wiki engine update). There is one other test you can run during your mash to see if you've had good conversion, an iodine test. The relevant part...
The iodine test is one way to determine whether there is any residual starch that lacks conversion. Just head to the local pharmacy and pick up a “tincture of iodine.” This is a small bottle that will last you about 10 years if you do not knock it over while performing the test.

It comes with a small dropper attached to the cap that allows you to lay a drop or two into a shallow sample of cool mash on a white dish. Be sure no grain material is present; this will yield a false positive. If the iodine color ranges from yellow to amber, conversion is complete. If the iodine turns dark purple to black, give the mash another 15 minutes and repeat the test. If a conversion is not reached after two hours, check your mash temperature. You may have undershot the target conversion-rest temperature.
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Re: Fermentation stops after 3 days!

Unread postby Crockett49 » Fri Jan 30, 2015 3:18 am

Thanks again for your replies. The three batches I have done are a Coopers based sparkling ale, Coopers based pale ale and a Lancaster styled milk stout.

The first two I used US-05 yeast (dry) and for the stout I used Bedford British ale yeast (WLP006 - liquid).

The lowest final gravity reading I got from the three brews was the second one (1.017) - pale ale. This is the one I made a starter out of the dried yeast (also made a starter for the stout).

Final gravity on the first brew was 1.023 and for the stout was 1.031.

All grains for all brews were mashed at the same time. None added later.

Looks like I'll be heading to the chemists for some iodine. I was thinking that perhaps there wasn't enough fermentable sugars in the wort for the yeast to do their thing with.

Tasted the stout yesterday and it tastes fine, not too sweet which I was thinking it was going to be.

Cheers

Craig
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Re: Fermentation stops after 3 days!

Unread postby Elderberry » Mon Feb 02, 2015 10:43 am

Have you tried calibrating your hydrometer? (Sorry if this has already been suggested)
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Re: Fermentation stops after 3 days!

Unread postby cpa4ny » Tue Feb 03, 2015 9:13 am

Crockett49 wrote:Thanks again for your replies. The three batches I have done are a Coopers based sparkling ale, Coopers based pale ale and a Lancaster styled milk stout.

The first two I used US-05 yeast (dry) and for the stout I used Bedford British ale yeast (WLP006 - liquid).

The lowest final gravity reading I got from the three brews was the second one (1.017) - pale ale. This is the one I made a starter out of the dried yeast (also made a starter for the stout).

Final gravity on the first brew was 1.023 and for the stout was 1.031.

All grains for all brews were mashed at the same time. None added later.

Looks like I'll be heading to the chemists for some iodine. I was thinking that perhaps there wasn't enough fermentable sugars in the wort for the yeast to do their thing with.

Tasted the stout yesterday and it tastes fine, not too sweet which I was thinking it was going to be.

Cheers

Craig


Bedford British yeast is a fairly highly attenuating yeast (as far as British yeasts go!) - I had it attenuate @ circa 78%

What was your starter size like? Was it on the stirplate?
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